#include <bits/stdc++.h>
using namespace std;
using ll = long long;
void Yes() {cout << "Yes\n";}
void No() {cout << "No\n";}
void YES() {cout << "YES\n";}
void NO() {cout << "NO\n";}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int P = 1000000007;

	int n;
	cin >> n;
	vector<int> a(n);
	for (int i = 0; i < n; i++) cin >> a[i];
	sort(a.begin(), a.end());
	if (a[0] == 0) {
		cout << -1 << endl;
		return 0;
	}
	long long pi = 1;
	for (int i = 0; i < n; i++) {
		long long subpi = 1;
		for (int j = 1; j <= a[i]; j++) {
			subpi *= j;
			if (subpi > P) {
				cout << P << endl;
				return 0;
			}
		}
		while (subpi--) {
			pi *= a[i];
			if (subpi > P) {
				cout << P << endl;
				return 0;
			}
		}
	}
	cout << P % pi << endl;

	return 0;
}